Chordates - Part 2 (Easy Explanation) Video Lecture | Biology for Class 9

hello friends this video on diversity in
living organisms part 22 is brought to
you by exam for your form no more fear
from exact so we can say that what
advantage do we get due to the presence
of notochord it provides internal
support it is it might not be present at
all stages of life but it is mean
sometimes during the lifetime of the
protocol it right so what is notochord
it is rod like structure running along
the back clear okay so now after these
protocols came up the vertebrates so
what where the vertebrates again as I
said vertebrates and flow deposits both
can be classified under the category of
coordinates so these are also classified
under coordinates corticoid means a
string and code or data actually this is
core data so cord means string and a
demeans group so the group of organisms
which have a cord or a string like
structure are called quartets so proto
chords where those who had a notochord
and vertebrates are who who are the
vertebrates then so let us see who are
the four debates they also have complex
body differentiation bodies bilaterally
symmetrical body made of three layers of
cells and stripclub elastic salami
cavity is present that is there see low
mate nodal cord is present so notochord
is present in this case also dorsal
nerve cord is also present so what does
this dorsal no of nerve God so this is
an additional
in case of vertebrates the dorsal north
quad is nothing but the north quad which
later gets modified to spinal cord and
brain so now you can understand this by
taking example of human beings in human
beings you would have seen that there is
a brain and the brain is associated to
them spinal cord so this dorsal North
quad actually modifies into the spinal
cord and the brain so where is this
dorsal nerve cord present so what is the
dorsal nerve God it later modifies
modifiers to brain and spinal cord and
well is the dorsal nerve cord present it
is a hollow cord in the dorsal part of
the notochord
what does dodson the word dorsal means
back right so it is a hollow called in
dorsal part of notochord so what is the
meaning of dorsal dorsal means back so
no two part is a one chord and the back
portion of the notochord is known as the
dorsal nerve cot and this dorsal nerve
cord later modifies to form a brain and
spinal cord so you can see that both the
proto cords and the vertebrates they
both had the notochord present but in
case of vertebrates the notochord became
little more complex due to the formation
of the arson nerves called which later
form of the brain and spinal cord
so the notochord basically supported the
dorsal nerve cord in case of vertebrates
so the structure becoming became little
more complex in vertebrates
it has organ system level of
organization because it has got all the
organ systems in place they are also
mobile right now why did they get this
name vertebrates that is because of the
presence of the vertebrate the backbone
what is that backbone as I said the
dorsal nerve cord that actually formed
with a backbone and that backbone is a
column of the vertebrae and from that
word vertebrae they were known as the
vertebrates due to the presence of the
vertebral column clear okay so let us
look at the differences between a
vertebrate and a quadrant many times
people think that vertebrates and
coordinates are the same thing but
please let me clarify that coordinates
are those who have a notochord any
organism with a notochord is corded
therefore all protocols also fall under
coordinate
because even they have a notochord and
all vertebrates also fall under cotton
because the vertebrates also have a
notochord but the difference is that
vertebrates also have a dorsal nerve
quad along with them note about it so we
can see that all vertebrates are
coordinates but all coordinates are not
vertebrates for example the proto
Corden's they are not vertebrates
invertebrates muscles are arranged in
paired masses in quadrats muscles are
not arranged in peor masses because in
vertebrates we have this backbone or the
spinal cord so from there all the muscle
muscles are arranged in paired masses
but in coordinates it is not necessary
spinal cord and backbone are present in
court it's not present in non vertebrate
quartets in case of audience because
coordinates not only includes
vertebrates but also includes the proto
cords and in proto corals we do not have
anything called dorsal nerve cord
therefore we do not have anything called
spinal cord or backbone right so this is
how we can distinguish between
vertebrates and quadrants now even other
vertebrates we saw that there were so
many organisms existing under
vertebrates that we needed to classify
them as neck
because we saw that those organisms were
also not exactly similar to each other
there are a lot of these similarities
amongst them also so there had to be a
basis of classification so on what basis
where they further classified based on
body design and structure because when
we talk about examples of vertebrates
birds human-beings lion monkey cat rat
rabbit they all fall under the 40 bits
but if you look at their structure or
their body design they look very
different right so be used on the body
structure and body design they were
further sub classified and so Wed weigh
the different categories into which they
were classified Isis amphibia reptile
Jia Aves
and malaria so these were the five
categories into which the vertebrates
were further classified so let us have a
look at each other thank you
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